Submission #43708

#	Time	Username	Problem	Language	Result	Execution time	Memory
43708		baactree	Split the sequence (APIO14_sequence)	C++14	100 / 100	987 ms	83524 KiB

sequence

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n, k;
ll dp[2][100005];
int par[205][100005];
ll sum[100005];
int arr[100005];
pair<ll, ll> dd[100005];
long double calc(pair<ll, ll> a, pair<ll, ll> b) {
	return ((long double)a.second - b.second) / (b.first - a.first);
}
void push(int i, int j,deque<int> &dq) {
	ll a = sum[j];
	ll b = dp[(i-1)&1][j] - sum[j] * sum[j];
	dd[j] = make_pair(a, b);
	while (dq.size() > 1 && (dd[dq.back()].second-dd[j].second)*(-dd[dq[dq.size() - 2]].first + dd[j].first) <= (dd[dq[dq.size() - 2]].second-dd[j].second)*(-dd[dq.back()].first + dd[j].first))
		dq.pop_back();
	dq.push_back(j);
}
int main() {
	scanf("%d%d", &n, &k);
	for (int i = 1; i <= n; i++) {
		scanf("%d", &arr[i]);
		sum[i] = sum[i - 1] + arr[i];
	}
	for (int i = 1; i <= k; i++) {
		deque<int> dq;
		int cur = i & 1;
		int pre = (i - 1) & 1;
		push(i,i,dq);
		for (int j = i + 1; j <= n; j++) {
			while (dq.size() > 1 && (dd[dq[0]].second - dd[dq[1]].second) <= sum[j]*(dd[dq[1]].first-dd[dq[0]].first))
				dq.pop_front();
			dp[cur][j] = dd[dq[0]].first * sum[j] + dd[dq[0]].second;
			par[i][j] = dq[0];
			push(i,j,dq);
		}
	}
	printf("%lld\n", dp[k & 1][n]);
	while (k) {
		printf("%d ", par[k][n]);
		n = par[k][n];
		k--;
	}
	printf("\n");
	return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:30:7: warning: unused variable 'pre' [-Wunused-variable]
   int pre = (i - 1) & 1;
       ^
sequence.cpp:22:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &k);
                       ^
sequence.cpp:24:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &arr[i]);
                       ^

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 21 / 21
• Subtask 6: 29 / 29